During the manufacturing of color paper it is necessary to cut the material lengthwise prior to its exposure, to reach suitable size for customer use. The photographic paper is formed in long, wide sheets, then spooled into large rolls. These rolls must be slit to suitable widths in a very accurate manner. It is important that the slitting be performed without damage to the sensitive photographic materials that are on the paper substrate. Further, it is important that slitting be performed without creation of substantial dust which might lead to undesirable contamination of picture surfaces after development.
Generally the knives utilized for cutting photographic papers have been arrangements of circular knives on shafts, with the paper being fed between the shafts with knives. The circular knives are brought together such that they touch and overlap slightly at the edge. It is common for one knife to have a square edge called the female knife, and the other knife to be ground at some angle, this knife called a male knife. In this way, many strips can be simultaneously slit from a wide sheet. U.S. Pat. No. 5,365,821--Munier et al discloses such a cutting device. EP 0 737 552--Blandin also discloses a knife and anvil cutting device.
The male circular knife generally has been applied to the upper or photosensitive side of the paper during slitting with the female knife in contact with the other side. However, in some instances, the reverse has been practiced. Typically the knife blade previously used has had a low rake angle, 10-15 degrees, ground on the edge, the low angle was used because it was an improvement over a square edge with no rake, and a mid range angle, such as 30 to 45 degrees.
In some instances, there has been found to be discoloration, such as yellow dye formation on the cut edge of photographic pictures after development. Further, there is a continuing problem with dirt and debris generated during cutting that will contaminate images during development.